My personal tracer is a mix of a few items that I use together to make tracing efficient, the main stay is the Greenlee 2007 kit with the live or dead circuit transmitter 0-600 volts, and the hand held receiver, with this I also use a common telephone/network toner receiver with the 60hz filter that will also hear the 2007 transmitter signal when locating a circuit I have no idea where it might run as it can hear the beeping from far off, and it will get louder as I get closer to it.
But at work we have both the Ideal 61-958 and 61-959 kits, I like the buttons on the 958 receiver better but the 959 has replaced the 958, I seen the 61-958 kit still around for about $1200.00 and the 61-959 kit for just a little more, the kit also has two types of transmitters (both do live 0-600 volts) besides the direct connection it has an inductive clamp on that makes it nice if you don't want to power down the circuit while making the connection,
you can also get the kit without the inductive clamp and battery pack, which we rarely use anyway at work, the 61-956 or 61-954 (led read out) both are a little lower in cost, but both do the same thing the receiver and direct connect transmitter in the 61-958 kit does and are both very good at finding where the wires run.
This is an area of tools where you get what you pay for, and while they are expensive paying for the convenience of being able to find the correct breaker on a live circuit is a great asset when your working in an office full of desk top computers, and turning off the incorrect breaker when someone is almost done inputting a whole bunch of data into their program leaves you feeling that you are about to be sent to the lions den for cat food
Almost all these transmitters used in these circuit tracers also modulate an audio signal into the tracing signal that a phone toner receiver with a 60hz filter will also pickup, so combining the two can also make finding and following the conductors a little easier, also if you do get the 61-958/959 kit then the inductive clamp on can also be used to follow conduit in the wall to some extent, we use it at work to find a conduit run when there are many runs together, even though they will have a few electrical connections between them from the mounting the signal strength is higher on the one with the transmitter on it.
I have got so used to using tracers so much that they have become like an extension of my body, its like now I can see/hear where the electrons flow and follow them, but they are addicting as I didn't bring mine to a job one time and I felt so handy capped that I had to go home and get it.